One or more implementations access a digital image and determine whether at least one portion of the digital image includes one or more bands having a difference in color. The determination is based on at least two candidate scales. One or more implementations access a digital image and assess at least a portion of the digital image for the existence of one or more bands having a difference in color. The assessing includes determining a fraction of pixels in the portion having a color value offset by an offset value from a color value of a particular pixel in the portion.